Heavy-duty electric switch



G. A. BURNHAM HEAVY DUTY ELECTRIC SWITCH Dec. 3, 1929.

Filed April 14, 1926 n Il V/AI... a. Il.

Patented Dec. 3, 1929 UNITED STATES PATENT OFFICE GEORGE A. BURNHAM, OFSAUGUS, MASSACHUSETTS, ASSIGNOR TO CONDIT ELECTRI- CAL MANUFACTURINGCORPORATION, OF SOUTH BOSTON, MASSACHUSETTS, A COR- PORATION FMASSACHUSETTS HEAVY-DUTY ELECTRIC SWITCH Application led April 14,

This invention relates to oil immersed electric switches adapted forinterrupting heavy currents at high voltages; and more particularly toheavy duty oil switches having separate enclosing casings for each phaseand a common actuating mechanism.

In the switch embodying this invention, the switch operating mechanismfor each phase unit, is disposed within an enclosed mechanismcompartment or well, between which wells communicating passages are.provided to accommodate the mechanism rods by which the several unitsare operated conjointly. Under certain conditions of circuitinterruption oil is thrown about in the switch casing and into themechanism well, from which it may escape or may pass to adjacentswitches of the set. A combustible mixture may also be formed in the gasexpansion space above the oil which mixture under proper conditions,

may burn or explode.

An object of this invention is to isolate the mechanism well from thegas expansion space of the switch, whereby to keep the oil andcombustible mixture, or explosive pressures, out

of the mechanism well and to isolate from each other. the oilcompartments of the switches of a multi-phase switching set.

A further object is generally to improve the construction andperformance of oil circuit breakers. i

Fig. 1 is a sectional elevation of an electric switch embodying theinvention.

-Fig. 2 isa detailed sectional elevation of two adjacent switch units ofa multi-phase switching set embodying the invention.

As here shown, the electric switch embodying this invention is adaptedto control a multi-phase electric circuit and to this end is providedwith several separate units, each comprising a switch casing andcooperating stationary Vand Amovable switch members. Said units are ormay be'identical and consequently the description of but one unit willsuiice. Each phase unit includes the enclosing casing 8 which is adaptedto contain oil or other suitable arc quenching fluid. Saidcasing'comprises a vertical cylindrical shell 10 of substantial heightopen at both ends, 50 forming the side walls of said casing, and

1926. Serial No. 102,070.

the concave plate 12 which is secured by means of rivets or by weldingin fluid tight relation within said shell near its lower end to providea bottom closure for the casing.

A switch frame 14 is secured to the top of said casing and forms atop-closure therefore and has a peripheral flange 16 which depends overthe top of the side wall of the casing. Said switch frame is providedwith an enclosed mechanism compartment or well 18 of more or lessrectangular shape which is disposed in the intermediate portion thereofand is formed by the parallel side walls 19 which extend both above andbelow the top wall of the switch frame. The' mechanism well is closed atthe bottom by the integral bottom wall 20 and at the top by theremovable wellcover 21.

Stationary switch members 22 ai'e cariied by said switch frame onopposite sides of the mechanism well and extend into the interior of theswitch casing and into the oil therein contained. The movable switchmember includes a bridging or brush member 211 which is adapted to beraised and lowered into and away from circuit-controlling relation withthe lower ends of said stationary switch members. Said brush member iscarried at the lower end of an insulating switch rod 2G which isextended upwardly and through an aperture 28 in the bottom wail 2O andinto said mechanism well and is connected with the switch operatingmechanism therein contained. Said operating mechanism may be of anyusual oisuitable construction which, preferably is adapted to guide theswitch rod for movement in a straight line. As heie shown, the mechanismincludes a guide link 30 one end of which is pivotally connected withsaid switch rod at the upper end thereof and the other end of which ispivoted to the upper end of a strut-link 32, the lower end of whichlatter link is pivotally connected with the switch frame. A bell-cranklever 84 is pivoted at 86 to the switch frame on the opposite side ofsaid switch rod; and the end of the long arm 38 of said lever ispivotally connected with an intermediate-point on said guide-link. Theshort arm 40 of said bellcrank lever is pivoted to an actuating rod 42fri which is adapted to be moved in a substantially horizontal directionby switch actuating mechanism (not shown) whereby to raise and lowersaid operating rod and said brush members and thereby to close andy openthe switches.

The mechanism wells of the several switch units are arranged to beconnected by communicating" passa-ges 45 through which said actuatingrod 42 is adapted to pass, by which the movable switch members of theseveral units are caused to be raised and lowered inunison. Saidpassages may be constructed of pipe-sections 46 whichxmay hwveflangeslat each end whereb they may be secured to the mechanism we ls of theseveral switch units in a fluid tight manner by means of boltsV 49:

In accordance with this invention, means are provided to isolate the`vmechanism well finemtheoil and:v gasspacev of the switch casing, wherebytokeep`r the oil' and? the' switch gases out of themechanism well' andalso to isolatie; the: casingsiol'f the'fvarious switchunit-s ofi amulti-phase switching set. To' this end, an insulating tubular member isdisposed to loosely'surround the switch; rod 26; The upper endofY saidmember 60= is fixed in a fia-ngc@ which is secured inia fiuid tightmannen to thebottom walllof the mechanism well about thel switchqod.opening therein. The lowerend 'o saidtubularfmember isextended beneaththe level of the oil in the casing and is terminated at about the'level: of the brush member`24 andthe. lower ends ofthestationary. switchmembers 22 in a metaal nose 64 which functionsy as ai guide forv the`switch rod; Said'y tubulin` member and its fittings areiconnectedtogether'in a substantially fluid tight mannerl so that a fluid tightconduit for theA switch rod isprovided whichl extends from'the-mechanismwell to alpoint below the oil"` level inthe easing.v While'the loweropen end ofisaid conduit which forms the opening for thel mechanismwell', is freelyopen, or at least there is a freerunningclearance'between the switch rod and the inner wallof the conduit, gastrom the gas-expansionspace above the oii in the casing cannot enter themechanism weil because of the body ofoil aboutthe lower end of the'conduit. No' appreciable amount ofoillcan enter the' mechanism wellthrough the conduit because of the small clearance space about theswitch rod, and the resistanceto fluid flew offered ther smallclearance. 'Il-he gases in the gas expansion spaceabove the oil canescape through the vent 66.1

I claim:

1. An electric switch having an oil containing enclosing casing whichhas a gas space above the oil and af mechanism well in the` gas spacewhich has an opening in its bottom: butl is otherwise sealedfrom theinteriorofthe: casing, means providing an oil seal for said opening,whereby to pre1 vent access of gas into said well from the interior ofsaid casing, and means independent of said well to vent the gas space ofsaid casing.

2. An electric switch haiving'an enclosing casing adapted to contain oiland having a gas expansion space above the oil, and a mechanism welldisposed mainly in said gas expansion space above the oil and' isolatedfrom fluid communication therewith, said well having an opening in thebottom which is beneath the oil, said casing having a ventingf passagewhich. is independent of said mechanism well.

3. A multi-phase switch apparatuscomprising a plurality of switch'casngseach adapted to contain oil andi gas expansion spaces above thekoil, intercomniunicating mechanism wells carried by said casings, and

having switch-rod openings in the bottoms thereof, and means to isolatesaid wel-ls from fluid communication with the gas expansion spaces ofsaid casings including-mea'nsto provideI oil seals for said openings,saidv wells thus being sealed from communicationwith tlie gas spaces ofsaidy casings, and said casings having venting passages for the gasspaces independent of said wells.-

4. A multipliase switching apparatus comprising a plurality ofV switchcasings each adapted to contain oil and having gas expansionr spacesabovev the oil, intercommunicating mechanism wells carried by saidrcasings mainly above the oil and isolated from said gas expansionspaces, said mechanism wells having openings in the bottoms thereofwhichl are beneath the oil-in saidcasing's, said wells thus being sealedfrom communication with' the gas spaces of said casings, and saidcasings having venting passages for the gas spaces independent of= saidwells.

5. An electric switch having an enclosing casing adaptedv to containoil, a mechanisin well disposed entirely above the oil level andisolated from the interior of said oil containing casing, said mechanismwell having a hollow extension depending into and terminated beneath thelevel of the oil, and a switch rod operable in said extensionsaid'casinghaving a venting passage which isindependent of said well.

6. An electric switch comprising the combinationof an oil containingenclosingicasing, stationary and movable switch members dependingintotheoil'of said casing, a-mechanism well carriedlby. the-upper partoffsaid casing', switclril operating mechanism contained thereinincluding a' rod which depends through an aperture in the bottom of saidwell and supports said movable switch membefr atx itslower end', and anvinsulating tube fixed dependently to saidmeehanism well in4 surroundingrelation with said rod and terminated at the lower ends of saidstationary switch members and constituting a guide for said rod thereat,whereby to guide said brush member into engagement with said stationaryswitch members.

7. An electric switch having an enclosing casing adapted to contain oiland provided with a gas expansion space above the oil, a mechanism welldisposed above the oil level and sealed against gaseous communicationwith said expansion space, a switch rod depending from said well intothe oil, and a tubular guide member surrounding said switch rod andhaving its upper end in gas tight connection with said well anddepending from said well through the gas eXpansion space and into theoil in said casing, the lower end of said tubular guide member beingopen only beneath the oil, and the side wall thereof being imperforate.

8. An electric switch comprising an enclosing casing adapted to containoil and having a gas expansion space above. said oil, an enclosedmechanism well disposed entirely above the oil and isolated from the gaseX- pansion space, switch operating mechanism disposed within said welland having an operative element extending through an opening in thebottom of said mechanism well and through the gas expansion space intothe oil of said casing, and means to prevent the entrance of gas fromsaid gas expansion space to said mechanism well through said openingcomprising a depending casing for said operative element and surroundingsaid opening and having a fluid tight connection with 'said well andextended downwardly through said gas expansion space and termin atedonly below the level of the oil within said casing, the side wall ofsaid depending casing being imperforate in said gas eXpansion space.

9. In an electric switch, the combination of a pair of enclosing casingsadapted to contain oil and gas expansion spaces above the oil, anenclosed mechanism well contained in the top of each of said casingsentirely above the oil therein, means providing a. communicating passageextending between said mechanism wells7 switch operating rods extendingthrough openings in the bottom walls of said mechanism wells, and meansto isolate said mechanism wells from the gas expansion spaces in saidcasings, said insolating means including guide tubes for said operatingrods, the upper ends of which tubes surround the openings in the bottomwalls of said wells and are secured to said walls in a gas tight mannerand the lower ends of which open only into the oil in said casings.

10. An electric switch having an enclosing casing adapted to contain oiland a gas er;` pansion space above the oil, a mechanism well disposed inthe upper part of said casing above the oil therein and having a bottomwall which is located above the oil and has an opening therethrough,switch operating mechanism contained in said well including a switch rodwhich extends through said opening into the oil,and an insulating tubehaving an imperforate side wall loosely surrounding said switch rod andhaving a flanged upper end which surrounds said opening and is carriedby and has a substantially gas tight connection with the bottom wall ofsaid well and which has a metal rod guiding member at its lower endwhich is submerged in the oil of the casing.

ll. An electric switch having an enclosing casing adapted to containoil, a mechanism well disposed above the oil and isolated fromcommunication with the interior of the casing and having a bottom wallwhich is located above the oil and has an opening therein, and a tubeliXed to and having a substantially gas-tight connection with saidbottom wall about said opening and extended downwardly therefrom andhaving its lower open end terminated only beneath the level and sealedby the oil in said casing.

In testimony whereof, I have signed my name to this specification.

GEORGE A. BURNHAM.

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